The invention relates to a tool head with spindle bearing arrangement, of which the bearings are supported with one bearing shell on a driven spindle with a tool holder for the driving of a tool and with the other bearing shell cooperating with a housing, whereby at least with one part of the bearing the relevant other bearing shell cooperates with a sliding piece, which can slide along the housing by means of a drive device, in the one sliding direction of which the spindle cooperating with the housing is interlocked therewith by means of a locking mechanism in a locking position for an operation with a stationary tool and in the other sliding direction of which it unlocks in an unlock setting for an operation with a rotating tool.
Comparable tool heads are configured for example as single-spindle tool heads to hold either stationary or rotating tools for rotary or milling operations taking place in manufacturing machinery. Furthermore such tool heads allow for automatic tool exchange. Particularly with rotary processing with a stationary tool, high stresses are generated in the spindle bearing arrangement, which then allow for rotary operation only within predetermined operational limits which are taken in order to avoid damage to the spindle bearing. Furthermore, operations can be realized generally only along a predetermined axis and operations of manufacturing along complicated structural geometric parts are not possible.
Such a tool head with spindle bearing arrangement is already known from DE 39 13 139 C2, in which for an operation with a stationary tool the spindle is locked in relation to the housing through a Hirth-type serration arrangement as locking mechanism. Compression pistons arranged around the exterior periphery of the spindle serve as drive device for the locking, which press an annular gear-tooth system against work surface annular gear-tooth systems of the housing and the spindle. The counter-pressure or reaction resulting from this is passed further to a sliding piece, which is supported on the interior and exterior bearing shells of the spindle bearing arrangement, in order in that manner in the interlocked or stopped position to avoid any axial play in the bearings by pressure forces being applied. With this known solution then the bearings of the spindle are interlocked for an operation with a stationary tool and the bearings because of that interlocking are being stressed. From a microscopic point of view, this leads with its sort of friction or diffusion welding to destruction of the bearings with reduction of the life of the tool head.
Starting from this state of the art the object of the invention is to disclose a universally useful tool head in comparison with the present state of the art, with which both milling and also rotary operation is possible with simultaneous unlocking of the spindle bearing arrangement when the stationary tool is used. Such an object is disclosed in the tool head having the features disclosed in claim 1.
Owing to the fact that according to the characterizing part of claim 1 the relevant other bearing shell of the one part of the bearing is enclosed at least partially by a sliding piece and that in either the locking or the unlocked position the sliding piece produces both the locking and unlocking by means of the drive device with a predetermined contact force, or when the stop mechanism is unlocked it engages on the housing, an effective relief of the bearing can be attained in the locked position with locking of the spindle, so that the operational limits in the stress-generating operation, particularly with stationary tool, can be carried further than with the known operation systems.
With the arrangement according to the invention during an operation with rotating tool, the sliding piece which surrounds the relevant part of the bearing for the spindle is interlocked by the force of the drive device against the housing and the flux of force is drained away from the spindle over the spindle bearing and into the housing by means of the sliding piece. When this occurs, the spindle bearing arrangement is highly stressed, which however is not important, since it is laid out analytically and of construction intended for just such a rotary or revolving operation. If processing is taking place with a stationary tool, for example for a rotary operation, the spindle preferably is provided, by means of the locking mechanism, with a Hirth-type serration arrangement, is tightly connected with the housing, and the sliding piece is mounted essentially free of forces and freely movable in the housing between stops. Since the sliding piece surrounds and encloses the relevant bearing on the associated bearing shell, such a bearing and bearing shell are also held free of forces and an application of potentially damaging force within the spindle bearing arrangement during operation with a stationary tool does not take place. This leads to a remarkable increase in the life of the tool head.
With one particularly preferred embodiment of the tool head of the invention, the sliding piece is formed of two separate sliding pistons which are slidable as drive device by means of fluid pressure in either one of the two sliding directions and can be returned in the relevant other sliding direction by means of an accumulator arrangement. By distribution of the function for the sliding piece into two component parts in the form of two sliding pistons, the described unlocking device can be mounted within the tool head directly in the area of the spindle, which conserves space.
In the case of another particularly preferred embodiment of the tool head of the invention, the one part of the bearing is arranged between the tool holder and the locking mechanism. With the known solutions (DE 39 13 139 C2) the arrangement is such that the locking mechanism in the form of the Hirth-type serrations is arranged between the tool holder and the spindle bearing arrangement. On the other hand, with the arrangement according to the invention, a rigid construction of the tool system becomes possible which enhances the operational qualitites especially with an operation using a stationary tool.
With another preferred embodiment of the tool head of the invention, the spindle is guided in the area of both of its ends rotatably in bearings, whereby the relevant bearings are arranged at the ends of the spindle lying adjacent to the tool holder, each with its relevant other bearing shell longitudinally slidable along the housing. Preferably it is thus provided that a gear-tooth system serves as locking mechanism for the locking of the spindle with the housing, and for the unlocking of the spindle the sliding piece can be moved into the center of the housing. Then on the one hand a secure locking is attained and on the other hand with the centering a certain and precise movement of the sliding piece between its end stops is attained.
In the case of another particularly preferred embodiment of the tool head of the invention, when the sliding piece is in locked position, the spindle is brought by the sliding piece into engagement with a drive shaft in interlocking position in such a manner that during its rotary movement the housing becomes pivotal with the spindle in predetermined positions. Preferably then the drive shaft is provided for the driving of the spindle carrying its tool, which drive shaft is connected with the spindle by means of a gear-tooth system, which in diametric opposition to one another alternately facilitates the locking and the driving of the spindle.
The tool head of the invention is designed in such a manner that it can be pivoted perpendicular to the rotary axis of the tool holder, in order thus to facilitate any operation with the tool in the desired linear path directions.
Insofar as an independent drive mechanism is provided in one preferred embodiment in order to hold the aforementioned drive shaft, then the pivot movement and the rotation of the tool holder can be embodied independently from one another, in order in such a manner to execute the most complex three-dimensional path geometries during the operation.
Other advantageous embodiments of the tool head are the object of the dependent claims.